1. Field of the Invention
This invention relates to a door latch system for a door of a switchgear enclosure and more particularly to a door latch system for a door of a switchgear enclosure wherein all the components of the door latch system are located outside the door for ease of repair.
2. Description of the Related Art
The terms switchgear and switchboard are general terms which cover metal enclosures which house switching and interrupting devices such as fuses, circuit breakers, relays, inner connections and supporting structures, including assemblies of these devices with associated fuses, interconnections and support structures used for the distribution of electric power.
Most switchgears presently produced include an exhaust system for venting gas and debris particles generated by an electric arc under arc-fault conditions. During an arc-fault explosion, the temperature and pressure inside the switchgear increase very rapidly and the rapid pressure build-up can damage the switchgear and its components. Exhaust systems such as that disclosed in US Published Patent Applications US 2009/0212022 and 2010/0258532 are designed to vent the gas and debris particles from the switchgear enclosure during an arc-fault explosion. Even though the venting systems of the prior art perform generally satisfactorily, the doors of the switchgear enclosure are subjected to large internal pressures which may cause the doors to “blow” open thereby subjecting workers in the area to possible injury.
Door latch systems have been previously provided in an attempt to prevent the enclosure doors from opening during an arc-fault explosion. However, the components of the prior art door latch systems are located within the door or within the enclosure at the inside surface of the door. If one of the components of the prior art door latch system should fail, it is impossible, or very difficult, to open the door to gain access to the failed component. In such a situation, it may be necessary to cut a large hole in the door to gain access to the failed component so that the door may be opened to perform the necessary repairs on the door.